sooty plug help

[sjw185]

Got a sooty spark plug on no1 cylinder.

Been chasing this one for a while now really starting to upset me

Changed out coil pack and proved coil pack ok with another cylinder.
Swapped Pos units about. checked wiring.
Had injectors tested and cleaned.
New spark plugs
New plug boots
Checked compression on all cylinders 10bar
removed injectors one at time but they all change engine noise so got no insight there?
No fault codes

Have no signs of missing or hesitation, just lumpy idle and stalling when braking at junctions sometimes?

Im just thinking could lean running affect just one cylinder? is my ECU faulty?

Any suggestions greatly recieved

[Knight Rider S4]

Hydraulic Tappet possiblity ,,,I had rich running on No1 on my Red 3B and that was the cause

[sjw185]

Hydraulic Tappet possiblity ,,,I had rich running on No1 on my Red 3B and that was the cause

Would that not show up with a compression test?
At the rolling road i was told she was running lean/possible injector clogged?

[T2Andy]

i thiink the rs2 set up needs\uses a different resiister in the ecu to make the injectors run propely its a different value to the aby one ,i also have a roug idle on that set up,but getting that sorted when i change the turbo and map.

[Smith_S2]

If the plug is sooty surely that is a sign of the cylinder 1 running rich?

Sooty/black plug engine runs rich in fuel
red/brown plug runs well complete combustion of all fuel
white plug engine has been run lean

I always thought that was a general rule with regards to spark plugs, correct me if i'm wrong.

What about the amplifier in the coil?

[Knight Rider S4]

Looking at this again ...As it is pointing to only one cylinder as been the issue it cancels out quite a few things, as you have done through checks it shows rich mixture , lean running when under boost so on

Checks I would be doing now would be checking the Inlet manifold and well sealed especially round No1 cylinder as if its leaking it could cause excess air , run rich on idle and lean running when under load

[sjw185]

If the plug is sooty surely that is a sign of the cylinder 1 running rich?

Sooty/black plug engine runs rich in fuel
red/brown plug runs well complete combustion of all fuel
white plug engine has been run lean

I always thought that was a general rule with regards to spark plugs, correct me if i'm wrong.

What about the amplifier in the coil?

4 plugs running healthy one running rich... or not firing points towards ignition system but ive flogged it to death with 3 different coil packs and 2 x Pos
Maybe Andy has a point with the mapping odd turbo?
Maybe try pulling the plugs after a while just at idle to see fit like?
thing is you would not notice if you didint look at the plug or rough idle as it goes like a scalded cat

[GazzaG60]

not alwasy easy to check plugs. even a small amount of idle will affect the look.

if all othe r4 are ok id look at that injector. easy test is swap 2 injectors over. on a standard inlet id expect no 1 to be the leanest. best airflow.

if 4 are good and one bad its not an injector inpedence issue. rought running will be if you put the wrong injectors in for a map.

[Rusty]

A little list off the top of my head:-

• Boost leak - causes rich running on boost.
• MAF - incorrect mixture due to faults signal.
• MFTS / Temp Sender - incorrect temperature relayed to ECU.
• Weak themostat - running in warm up mode all the time (<80deg).
• Lambda - incorrect mixture on part load.
• Oil from breather system gunging things up.

HTH

1 is the furthest from the inlet on OE inlet manifold so any small leaks would be seen there, could also be a crack in the head at the spark plug causing a small leak. At least rich is relatively safe compared to lean!

[sjw185]

Good point on the injectors its a easy and cheap test to do, had dismissed the injectors as had them cleaned and tested.

Got a leak test kit so will try that too before i start buying parts.

cheers

[GazzaG60]

after that id swap a plug to a different port to see if its that.

in fact id do that first.

1. swap plugs about
2. swap injecotrs about.

if issue moves with 1 then plug is at fault.
if issue moves with 2 its injector.
if issue remains check the plug to head seating.

[Smith_S2]

Stevie I have a bunch of spare plugs if you are in need of some quickly, Bosch and NGK

Goodluck, hope you get it sorted!

[sjw185]

cheers, will do some tests when the snow stops

[GazzaG60]

my s2 was originally from aberdeen too. must have sold a lot up there to the oil tycoons?

[sjw185]

cant belive it! it was the Injector!!!!
Swapped injector no 1 to cylinder 3 and went for a run came back with sooty plug
Had them cleaned and tested late last year so they are going to feel my wrath come monday

Think the injectors came from MRC (rs2 replicas) maybe see if i can buy just one.
failing that i could sell them as a set of four and get some new ones.

Thanks everyone you saved a s2 from getting torched